There are a number of applications in which it is of interest to detect or image an object. The object may be imaged or detected in daylight and/or in darkness, depending on the application. Examples of such applications include, but are not limited to, personal safety and security.
Security applications typically use motion detectors to trigger alarms, bright floodlights, or video cameras when a sufficiently heavy or warm mass moves within their range. Motion detectors are used, for example, in home security systems and commercial security settings. Unfortunately, motion detectors do not always discriminate between human, animal, and inanimate objects. Thus, a large object, such as a dog or a truck, that moves near a motion detector may be detected and unnecessarily create a false positive by triggering an alarm, floodlight, or video camera. False positives result in extra costs for the individuals, businesses, and police departments that are required to respond to all triggered events.